Lightweight, foldable stools and chairs are used in camping and other outdoor uses because they can easily be carried, stored compactly and are quick and easy to setup.
Some of the simplest devices for portable seating have been triangular or square seats stools with 3 and 4 legs. These simple designs are light compact, but lack strength and also comfort because they cannot easily have a back support.
There are many varieties in prior art, showing a constant trend to improve upon weight, foldability, portability and comfort. One such variety is illustrated in FIG. 1.
Inventor is aware of U.S. Pat. No. 4,184,711 issued to Wakimoto Jan. 22, 1980, a four-legged chair with the legs pivotally-coupled by an external center hinge and two back support uprights each hinged separately to a leg. Wakimoto's patent offers improved compactness by eliminating the horizontal seat supports. However, the external center hinge and back support tubes would not adequately support the weight of a large person.
Inventor is also aware U.S. Pat. No. 4,290,643 issued to Logan Sep. 22, 1981, a folding chair comprising a complicated network of eight rigid members, six tension cables, and a complex fabric cover. Although the closed bundle folds in a substantially parallel arrangement for collapsibility, the complex fabric cover can easily be stressed, especially after the material has been exposed to the sunlight over time. Also, it is not seen as an improvement over prior art in regards to ease of assembly.
Inventor is also aware U.S. Pat. No. 4,595,232 to Glenn et al. Jun. 17, 1986 which shows a four-legged chair with legs put together as two front-to-back X-shaped frames, two side-to-side horizontal seat supports connecting the X-frames, and two posts extending upright from leg sockets to hold a fabric backrest. A "spacer bar" reinforces the posts above the backrest to eliminate the flex of Wakimoto's art but adds a hard surface causing user discomfort. However, this design does not improve the collapsibility or lightweight features of existing art. Also, the frame design would not be stable under a heavy person.
Inventor is also aware U.S. Pat. No. 4,807,930 to Helfrich Feb. 28, 1989, which shows a four-legged chair with legs, put together using four X-shaped frames, supporting a fabric seat and a fabric backrest, but would be limited in its ability to handle the weight of a large person or the abruptness of a person dropping or plopping down onto the chair.
Inventor is also aware U.S. Pat. No. 5,718,473 issued to Lynch Feb. 17, 1998, which is lightweight and collapsible chair, but would also be limited in its ability to handle the weight of a large person or the abruptness of a person plopping down onto the chair.